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Download Header Only messages appear blank
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Outlook: Microsoft Outlook for Microsoft 365 MSO (Version 2506 Build 16.0.18925.20076) 64-bit
MDaemon Connector: 8.0.2 64-bit
MDaemon: 25.03 64-bit
So, our default deployment has had the "Download Headers Only" option selected. Everything has been fine, until the last week or so.
Suddenly, people are clicking on a message only to find the preview pane, after the standard flashes you get while Outlook should be retrieving the body, blank. Sometimes, if you click on another message, and then click back on the first message, the body appears. Other times, it never appears. You can even double-click and open it in its own window, and it's still blank.
Of course, you can turn off the "Headers Only" option, and from then on things are ok -- but not for messages downloaded previously when the headers only was on -- those remain problematic. It seems the only answer is to create a new profile, turn off headers only, and re-download the folder.
Again, we've been using this for some time now, and this just started.
Dave
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What does the MDaemon-Connector log on the MDaemon server show is happening?
Is there AV running on the server? Are the MDaemon directories excluded?
Is there an AV gateway that is intercepting IMAP traffic and scanning it?
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I'll have to look into the logs -- and maybe try to force it to happen in order to check... we've been switching people to disable the headers only option. But then it'll happen to messages that were already in, say, their sent folder -- and no matter what, they can't get them to open. I'm trying some things, and I'll report back.
The only AV on the server is Defender, and then we have SentinelOne's EDR software. We have an exclusion for SentinelOne for all the MDaemon folders. I'll check Defender.
Thanks,
Dave
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Our user base has experienced this phenomenon for years. It seems to come and go for users, too. MDaemon support looked into it and they suggested unchecking the "Download Headers Only" which solved it for about a year. But it has started again recently with a vengeance for all users, regardless of that setting. I'm guessing it started after the latest upgrade to 25.0.3 but maybe that's just coincidence.
It's weird, almost like there is some kind of cache issue.
Arron - what should look for in the log to help me troubleshoot this?
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@MARTIN Arron is out of the office at the moment. I would recommend looking at the steps he already suggested for the original poster:
What does the MDaemon-Connector log on the MDaemon server show is happening?
Is there AV running on the server? Are the MDaemon directories excluded?
Is there an AV gateway that is intercepting IMAP traffic and scanning it?
In addition, what version of Outlook are your users on, and are they all using the same version of the MDaemon Connector client?
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Thanks for your response.
We use no AV gateway. We currently have Crowdstrike Falcon NGAV on server & endpoints since 2022, but for three years before that there was no antivirus whatsoever. To test further I have a plain vanilla Windows 11 installation myself (no AV) and the issue still manifests with 64-bit Outlook 2021. In our case, the problem occurs either with or without antivirus.
We use virtually ALL versions of Outlook (2013, 2016, 2019, 2021, and 365) and a combination of 32-bit and 64-bit flavors. All versions behave the same and always have, except for the brief time it appeared that 64-bit was the resolution to this problem. Also, the latest MD Connector is installed on each endpoint.
My question for Arron was that I want to review the MDaemon-2025-08-03-MDaemon-Connector.log but I need to know what elements I'm looking at to spot potential problems.
Thanks.
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We are looking for commands that take a long time to process in the log file. The client is requesting the content from the server. If the server is causing the slowness, then the log should show it.
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Thanks! According to the log, all actions between a specific Outlook client and server measure in milliseconds, never more than 1 second. How long is too long?
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How long is too long?
Commands taking less than a second are unlikely to be the cause of a delay.
Can you describe the issue you are having in detail?
The original post describes the issue as the body being blank when a message is loaded in the preview pane or when the message is opened. When you are using download headers only this is most likely a delay in retrieving the message data from the server. If a user with download headers only disabled experiences the same issue, its is likely caused by something different, as the client should already have the message data downloaded.
In that case, I'd start by looking at the local cache. How large is the LocalCache.db file? What is Purge message body of messages older than, set to? When was the last time it was purged and compacted?
How large is the Attachments directory?
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My issue is exactly as described in David's post. In our case we had globally unchecked the "download headers only" per MDaemon support's recommendation. Last purge date is current and last compact date is current.
For me, the LocalCache.db is 77MB. However, I just created a brand new Outlook profile and intentionally set "Send/Receive checks mail in all folders" to force a complete sync and that LocalCache.db is 136MB. Curious about the size disparity I looked in the Attachments folder of the new profile (3400 files, 281MB) and found old, large attachments from 5 years ago. Many are definitely old Calendar event attachment items.
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Your definition of current and my defintion could be very different. I'll just assume that current means within the past week.
How long does it take for the message to load in the preview pain? Does it take about the same amount of time to load if you doulble click the message to open it?
Please delete the old files from the attachments directory, restart Outlook and see if that makes a difference.
Does this issue occur with every message you attempt to read? Does it happen with both the preview pane and if you double click a message to open it? Does it also happen with messages in subfolders?
After creating a new Outlook profile and allowing it to sync all data, is the issue still occurring?
What version of Outlook is being used on this machine? Is it 32 or 64 bit?
Are there any plugins being used in Outlook other than MDaemon Connector?
How much memory is Outlook using?
If you put Outlook in Offline mode, does the same thing occur?
Is there any AV running on the workstation? If you exclude the localcache.db file and the Attachments directory does the behavior change?
If you restart Outlook does the behavior change?
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Lots of good questions!
Current means within a few minutes ago (or last time user exited Outlook); and it appears to successfully purge/compact upon exit.
If the message is not instantly blank, as the OP describes, then any message loads immediately after the preview pane slides back and forth, which usually takes about 1-2 seconds.
For my original 64-bit profile this behavior typically occurs on every message over 30 days old. I say "typically" because the behavior is inconsistent. It might also happen on messages received in the past minute. The behavior will sometimes "go away" after restarting Outlook or the PC, but then it eventually reoccurs within minutes or hours.
Yes this behavior happens on subfolders, too.
I had a 32-bit user create a fresh Outlook profile a few days ago and surprisingly the preview pane behavior has not yet manifested. This has been our go-to workaround for many years, but it doesn't resolve it because the behavior always returns.
All versions and flavors of Outlook 2013 thru 2021 and 365. Both 32-bit and 64-bit.
No plugins.
Good suggestion about Outlook memory use. I would need to monitor throughout the day, but currently seems to hover at 278MB.
With Outlook in Offline mode, the preview pane does NOT slide/bounce back and forth. But many of the emails are blank now in preview pane AND when opened.
AV is NOT running on my workstation but I've tested exclusions on server and endpoints. So I've tested every option with or without AV. For us, AV (Crowdstrike Falcon) does not affect this issue.
Restarting Outlook has no effect on the preview pane erratic behavior or the blank content issue. Only creating a new profile resolves (temporarily) the problem for us.
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Forgot to mention: When I changed from "Work Offline" back to online, the previously blank emails would display AFTER the preview pane did its slide left-right-left.
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Are there any Outlook rules being applied to the message that have a blank body? For example, is an Outlook rule moving the message to another folder?
When the issue occurs and the message body isn't shown, if the user logs into webmail and moves that message to a new folder, will MDaemon Connector then download the body of the message?
If you create a new profile, turn off the option to purge messages older than X days, and then allow it to download all the message content, does the issue return?
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No rules for most. Same behavior with or without rules.
For the 32-bit users I've had them re-create a new profile. They deleted the old profile so I cannot test your suggestion to move the message to a new folder. That's interesting, and we'll try it the next time someone alerts me to the problem.
Same with the purge option on a new profile. Although I will admit that, except in the case of 32-bit users with numerous email folders and many attachments (5GB+), just the act of creating a new profile fixes the problem TEMPORARILY. A new profile is like magic, but within a few days of normal use it resumes the blank emails and jerky preview pane behavior.
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Update:
Inbox contains 722 messages (total 129MB) going back six months.
My recently created 64-bit profile just started the same behavior of the preview pane collapsing/resizing. The preview pane does a quick blink-blink, then collapses causing the inbox to stretch to fill the space, then the preview pane re-expands to display content. This occurs for every single email over 30 days old. Once previewed the behavior stops for that message.
It behaves like a cache issue.
If I double-click to open a message older than 30 days that hasn't yet been "cached", it displays a brief window in its attempt to open the message, but closes immediately as the preview pane does its collapse/resize thing, and then I must double-click the message again to open it successfully. In other words, double-clicking on an "uncached" message does not work as expected.
Likewise, if I turn OFF the preview pane and scroll down to an "uncached" message, double-click it a similar behavior occurs where the message opens, then immediately closes so fast that I cannot see its contents, then it flickers back open to display properly.
Of course, I just created a brand, new profile with Connector and Outlook works normal (preview pane, opening messages, etc). Based on past experience this will only last a month or two and the cycle will repeat.
There is either a rogue setting, or something seriously wrong with the Connector.
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Previously I understood the problem to be that the message content was blank for some messages when loading them in the preview pane and when opening the message. In your last post it seems like the issue is the preview pane blinks a couple of times before loading the actual message content. Are you seeing both behaviors just at different times? If you'd could record a screen capture both behaviors occurring and upload them to us, it would be very helpful.
You can upload it to https://mdaemon.sharefile.com/r-rc3922c1eed334d4dbf5e34f0bd04ccd6. Don't forget to click the upload button and please let us know the name of the file you uploaded.
Can you also confirm that you have "Download headers only" enabled when experiencing the preview pane blinking. And that an "uncached" message is one that has not had the message body downloaded from the server yet? Or is an "uncached" message one that has been download and then had the message body purged from the local cache?
In your new profile, that is working normal, if you set the option for purge message body of messages older than X days to 0 so that it never purges them, does the issue with the message body not loading return? Does the issue with the preview pane blinking before loading return?
